Method for making a heat sink device and product made thereby

ABSTRACT

A method for making a heat sink device includes the steps of: (a) providing a first heat conducting plate and a second heat conducting plate, the first heat conducting plate being folded to form a plurality of first connecting parts and a plurality of fin parts, the second heat conducting plate including second connecting parts corresponding to the first connecting parts of the first heat conducting plate; (b) cold pressing the first connecting parts respectively against the second connecting parts so as to connect respectively the first connecting parts to the second connecting parts; and (c) heating and press forging the first connecting parts and the second connecting parts so as to form porosity-free joint parts between the first and second connecting parts.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority of Taiwanese application No. 091111678, filed on May 31, 2002.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The invention relates to a method for making a heat sink device, more particularly to a method for making a heat sink device by complex processing. The invention also relates to a heat sink device made by the method.

[0004] 2. Description of the Related Art

[0005] Referring to FIG. 1, a conventional heat sink 5 generally includes a base plate 51 and a plurality of fin elements 52 mounted formed on the base plate 51. The bottom surface of the base plate 51 of the heat sink 5 is mounted directly or indirectly on a heat source 6, such as a central processing unit. The heat generated by the heat source 6 is transmitted from the heat source 6 to the fin elements 52 via the base plate 51, and is heat-exchanged with the ambient space via the fin elements 52 so as to reduce the temperature of the heat source 6.

[0006] The method for making the heat sink 5 is generally classified into two categories, i.e., an integral forming manner, and a complex processing manner. The method for making the heat sink 5 in the integral forming manner is conducted by extruding of aluminum material, die casting of copper material, or metallurgical forming of metal powdery material. The shortcoming of this method is that the density of the fin elements 52 is limited due to restrictions in the design of the mold cavity for making the heat sink 5. Therefore, the efficiency for heat dissipation is limited. On the other hand, in the complex processing method, the fin elements 52 are respectively fastened on the base plate 51 by welding or by riveting. The advantage of the complex processing method lies in that the density of the fin elements 52 is not limited. However, the disadvantage of the complex processing method resides in that the problem of thermal resistance may be present due to differences in that heat conductivity of the materials for making the heat sink 5. In other words, the heat conductivity factor of the weld material may be lower than that of the materials for the fin elements 52 and the base plate 51. Thus, heat conductivity will be resisted at the welding locations between the base plate 51 and the fin elements 52. Furthermore, the riveting joints between the base plate 51 and the fin elements 52 are formed in a point-connection manner, which will result in localized stress at the joints during processing, and which will lower the heat conductivity.

SUMMARY OF THE INVENTION

[0007] Therefore, the object of the present invention is to provide a method for making a heat sink device, which can overcome the aforesaid shortcomings of the prior art.

[0008] The method for making a heat sink device according to this invention includes the steps of:

[0009] (a) providing a first heat conducting plate and a second heat conducting plate, the first heat conducting plate being folded to form a plurality of first connecting parts and a plurality of fin parts, each of which is formed between two adjacent ones of the first connecting parts, the second heat conducting plate including second connecting parts corresponding to the first connecting parts of the first heat conducting plate;

[0010] (b) cold pressing the first connecting parts of the first heat conducting plate respectively against the second connecting parts of the second heat conducting plate so as to connect respectively the first connecting parts of the first heat conducting plate to the second connecting parts of the second heat conducting plate; and

[0011] (c) heating and press forging the first connecting parts of the first heat conducting plate and the second connecting parts of the second heat conducting plate so as to form porosity-free joint parts between the first and second connecting parts of the first and second heat conducting plates.

[0012] Another object of this invention is to provide a heat sink device made by the aforesaid method. The heat sink device according to this invention includes a first heat conducting plate, a second heat conducting plate, and porosity-free joint parts. The first heat conducting plate has a plurality of first connecting parts and a plurality of fin parts, each of which is formed between two adjacent ones of the first connecting parts. The second heat conducting plate has second connecting parts corresponding to the first connecting parts of the first heat conducting plate. Each of the porosity-free joint parts is formed between one of the first connecting parts and a corresponding one of the second connecting parts by cold pressing said one of the first connecting parts against the corresponding one of the second connecting parts followed by heating and press forging said one of the first connecting parts and the corresponding one of the second connecting parts.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiments with reference to the accompanying drawings, of which:

[0014]FIG. 1 is an exploded perspective view of a conventional heat sink;

[0015]FIG. 2 is an exploded perspective view of the first preferred embodiment of a heat sink device according to this invention;

[0016]FIG. 3 is an exploded perspective view of the second preferred embodiment of a heat sink device according to this invention;

[0017]FIG. 4 is a perspective view showing a pre-positioning step of the preferred embodiment of a method for making a heat sink device according to this invention;

[0018]FIG. 5 is a schematic view showing a heat and press forging step of the preferred embodiment of the method according to this invention; and

[0019]FIG. 6 is a perspective view of the first preferred embodiment of the heat sink device according to this invention, which is adapted to be used with a heat source.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0020] Referring to FIGS. 2 and 6, the first preferred embodiment of a heat sink device according to this invention is shown to include a first heat conducting plate 2, a second heat conducting plate 1, and porosity-free joint parts 7. The first heat conducting plate 2 can be made of copper or aluminum. The first heat conducting plate 2 has a plurality of first connecting parts 22 and a plurality of fin parts 21, each of which is formed between two adjacent ones of the first connecting parts 22. Preferably, each of the fin parts 21 is provided with holes 211 for enhancing the convection of air so as to improve the efficiency of heat removal from the fin parts 21. Furthermore, each of the fin parts 21 is preferably formed with a plurality of recesses 212 so as to increase the area for air contact and to further enhance the efficiency of heat dissipation. The material for the second heat conducting plate 1 may be the same as or different from that for the first heat conducting plate 2, and can also be copper or aluminum. The second heat conducting plate 1 is used as a base plate for contacting the heat source 6 either directly or indirectly. The second heat conducting plate 1 has second connecting parts 11 corresponding to the first connecting parts 22 of the first heat conducting plate 2. Each of the porosity-free joint parts 7 is formed between one of the first connecting parts 22 and a corresponding one of the second connecting parts 11.

[0021] The method for making the heat sink device of the present invention includes the steps of:

[0022] (a) providing a first heat conducting plate and a second heat conducting plate:

[0023] The first heat conducting plate 2 is folded to form a plurality of first connecting parts 22 and a plurality of fin parts 21. Each of the fin parts 21 is formed between two adjacent ones of the first connecting parts 21. The second heat conducting plate 1 includes second connecting parts 11 corresponding to the first connecting parts 22 of the first heat conducting plate 2.

[0024] (b) cold pressing:

[0025] The first connecting parts 22 of the first heat conducting plate 2 are cold pressed respectively against the second connecting parts 11 of the second heat conducting plate 1 so as to connect respectively the first connecting parts 22 of the first heat conducting plate 2 to the second connecting parts 11 of the second heat conducting plate 1.

[0026] Preferably, in order to enhance the connection of the first connecting parts 22 of the first heat conducting plate 2 to the second connecting parts 11 of the second heat conducting plate 1, a pre-positioning step can be conducted before the cold-pressing step (b). Referring to FIG. 4, the pre-positioning step is conducted by folding each of two marginal ends 13 of the second heat conducting plate 1 over a corresponding one of two marginal ends 23 of the first heat conducting plate 2 to embrace the marginal ends 23 of the first heat conducting plate 2.

[0027] Alternatively, the pre-positioning step can be conducted by roughening the first connecting parts 22 of the first heat conducting plate 2 and the second connecting parts 11 of the second heat conducting plate 1, or by forming recess-and-protrusion interengagement elements on the first connecting parts 22 of the first heat conducting plate 2 and the second connecting parts 11 of the second heat conducting plate 1.

[0028] (c) heating and press forging:

[0029] The first connecting parts 22 of the first heat conducting plate 2 and the second connecting parts 11 of the second heat conducting plate 1 are heated and press forged so as to form porosity-free joint parts 7 between the first and second connecting parts 22,11 of the first and second heat conducting plates 2, 1. The heating process can be conducted by high frequency induction heating, far infrared ray heating, high energy laser heating, high current resistance heating, hot air heating, or the like. The purpose of the heating is to soften or melt locally the first and second connecting parts 22,11 of the first and second heat conducting plates 2,1 so as to reduce localized stress between the first and second connecting parts 22,11 of the first and second heat conducting plates 2,1, and to enhance the intimate connection therebetween as well. The press forging process is conducted to complex the first and second connecting parts 22,11 of the first and second heat conducting plates 2, 1 so as to form the porosity-free joint parts 7 therebetween. The press forging process can be conducted in any suitable manner well-known in the art depending on the processing conditions. Referring to FIG. 5, in the preferred embodiment, a plurality of rolls 4 are provided between two adjacent fin parts 21 to conduct the press forging process. Other known processing operations, such as casting, punching, perforating, or the like, may be employed to accomplish the press forging.

[0030] A cooling step is conducted after the heating and press-forging step (c) so as to produce the heat sink device having the porosity-free joint parts 7 between the first and second connecting parts 22,11 of the first and second heat conducting plates 2,1.

[0031] Referring to FIG. 3, a second preferred embodiment of the heat sink device according to this invention is shown, in which the second heat conducting plate 1 includes a base layer 4 and a highly heat conducting layer 3 overlying the base layer 4. The second connecting parts 11 are disposed on the highly heat conducting layer 3. In the preferred embodiment, the first heat conducting plate 2 and the base layer 4 of the second heat conducting plate 1 are independently selected from a group consisting of a copper substrate and an aluminum substrate. The highly heat conducting layer 3 of the second heat conducting plate 1 is a metal substrate having a relatively high heat conductivity factor as compared to the metal substrate for the first heat conducting plate 2 and the base layer 4 of the second heat conducting plate 1. Preferably, the highly heat conducting layer 3 of the second heat conducting plate 1 is suitably selected from a group consisting of a silver substrate and a carbon substrate. The method for making the second preferred embodiment of the heat sink device of this invention is substantially identical to that for the first preferred embodiment.

[0032] Referring to FIG. 6, when applied to a heat source 6, if the surface of the heat source 6 is provided a protrusion 61, the second heat conducting plate 1 can be formed with a recess 12 corresponding to the protrusion 61 by, for example, punching in advance so as to enhance the intimate contact between the heat sink device and the heat source 6.

[0033] In view of the aforesaid, the following are some of the advantages of the present invention over the prior art:

[0034] 1. The configuration of the first heat conducting plate 2 can be designed depending on the size and shape of the applied product, the air convection conditions, etc. Therefore, the design of the first heat conducting plate 2 is relatively flexible.

[0035] 2. Since the porosity-free joint parts 7 are formed by the aforesaid complex processing steps (i.e., the cold pressing and the heating and press forging) upon the first connecting parts 22 and the second connecting parts 11, the aforesaid shortcomings of the prior art can be overcome.

[0036] While the present invention has been described in connection with what is considered the most practical and preferred embodiments, it is understood that this invention is not limited to the disclosed embodiments but is intended to cover various Arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements. 

I claim:
 1. A method for making a heat sink device, comprising the steps of: (a) providing a first heat conducting plate and a second heat conducting plate, said first heat conducting plate being folded to form a plurality of first connecting parts and a plurality of fin parts, each of which is formed between two adjacent ones of said first connecting parts, said second heat conducting plate including second connecting parts corresponding to said first connecting parts of said first heat conducting plate; (b) cold pressing said first connecting parts of said first heat conducting plate respectively against said second connecting parts of said second heat conducting plate so as to connect respectively said first connecting parts of said first heat conducting plate to said second connecting parts of said second heat conducting plate; and (c) heating and press forging said first connecting parts of said first heat conducting plate and said second connecting parts of said second heat conducting plate so as to form porosity-free joint parts between said first and second connecting parts of said first and second heat conducting plates.
 2. The method as claimed in claim 1, further comprising a step of roughening said first connecting parts of said first heat conducting plate and said second connecting parts of said second heat conducting plate so as to pre-position said first connecting parts on said second connecting parts before step (b).
 3. The method as claimed in claim 1, further comprising a step of forming recess-and-protrusion interengagement elements on said first connecting parts of said first heat conducting plate and said second connecting parts of said second heat conducting plate so as to pre-position said first connecting parts on said second connecting parts before step (b).
 4. The method as claimed in claim 1, further comprising a step of folding a marginal end of said second heat conducting plate over a marginal end of said first heat conducting plate to embrace said marginal end of said first heat conducting plate so as to pre-position said first connecting parts on said second connecting parts before step (b).
 5. The method as claimed in claim 1, wherein said second heat conducting plate includes a base layer and a highly heat conducting layer overlying said base layer, said second connecting parts being disposed on said highly heat conducting layer.
 6. The method as claimed in claim 1, wherein said first and second heat conducting plates are independently selected from a group consisting of a copper substrate and an aluminum substrate.
 7. The method as claimed in claim 5, wherein said first heat conducting plate and said base layer of said second heat conducting plate are independently selected from a group consisting of a copper substrate and an aluminum substrate, said highly heat conducting layer of said second heat conducting plate being selected from a group consisting of a silver substrate and a carbon substrate.
 8. A heat sink device, comprising: a first heat conducting plate including a plurality of first connecting parts and a plurality of fin parts, each of which is formed between two adjacent ones of said first connecting parts; a second heat conducting plate including second connecting parts corresponding to said first connecting parts of said first heat conducting plate; and porosity-free joint parts each formed between one of said first connecting parts and a corresponding one of said second connecting parts by cold pressing said one of said first connecting parts against said corresponding one of said second connecting parts followed by heating and press forging said one of said first connecting parts and said corresponding one of said second connecting parts.
 9. The heat sink device as claimed in claim 8, wherein said second heat conducting plate includes a base layer and a highly heat conducting layer overlying said base layer, said second connecting parts being disposed on said highly heat conducting layer.
 10. The heat sink device as claimed in claim 8, wherein said first and second heat conducting plates are independently selected from a group consisting of a copper substrate and an aluminum substrate.
 11. The heat sink device as claimed in claim 9, wherein said first heat conducting plate and said base layer of said second heat conducting plate are independently selected from a group consisting of a copper substrate and an aluminum substrate, said highly heat conducting layer of said second heat conducting plate being selected from a group consisting of a silver substrate and a carbon substrate. 